Cuda error: illegal memory access

both standalone and ps plugin version giving me this error when I change compression to BC1 BC3 and clicking preview compressed.
TT 2023.3.0
RTX 2080Ti on latest gameready drivers in win11
tried downgrading cuda to 11.8, problem persist

Couldn’t find older releases to see if its the same so can’t troubleshoot any further?
Any ideas would be much appreciated


Hi @adevra, thanks for reporting this bug! I can confirm this crash on an RTX 2080 Ti and am currently investigating the root cause.

It looks like the workaround of making the Texture Tools Exporter switch to CPU-only processing by loading the
no-cuda.dpf preset (a preset that contains only the --no-cuda option) works, but it makes processing slower.

Here’s the direct link as well to 2023.2.0:

Thanks again,


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Hi @adevra! I’m happy to say I think we’ve fixed this in today’s Texture Tools Exporter 2023.3.1 / NVTT 3.2.3 release. Could you download the new version and confirm whether it fixes it for you?

It turned out one of the new functions used for BC1-BC3 compression in NVTT 3.2.2 indexed out-of-bounds of CUDA shared memory. Interestingly, this caused a crash on an RTX 2080 Ti GPU, but not on an RTX 3090 GPU! We’ve fixed this out-of-bounds access, and improved the robustness of the Exporter’s code around it so that even if a different kernel fails and you get another message like this, you should be able to click “OK” and have the Exporter switch to CPU processing correctly.

Hope this helps!